Steel alloy usable for valve seats and the like



2,823,993 Patented Feb. 18, 1958 [ice 2,823,993 STEEL ALLOY USABLE FOR VALVE SEATS THE LIKE Gerhard Kubera, Blumberg, Baden, Germany, assignor to Alfred Teves, Maschinenund Armaturenfabrik K. G., Frankfurt am Main, Germany No Drawing. Application July 25, 1956 Serial No. 599,931

Claims priority, application Germany July 16,1955 4 Claims. (Cl. 75-126) The present invention relates to the manufacture of steel alloys, and has particular reference to a novel composition of matter for forming steel alloys usable, for instance, in valve cones.

It has heretofore been customary in the manufacture of valve cones to employ as a rule, a chrome-silicon steel consisting of 0.4-0.5% carbon, 3-3.5 silicon, 0.3-0.5% manganese, 8-9% chromium and the remainder iron. A steel of this composition has sufliced until lately, but is now no longer satisfactory due to constantly increasing casting strains in the motor, particularly With respect to resistance to deformation at high temperature and with relation to non-scaling properties. In many instances it has therefore been necessary to employ in the manufacture of valve cones a nickel-chrome steel of 0.4-0.5%, 1.2-3.5 silicon, 0.6-1% manganese, 14-17% chromium, 12-15% nickel, 23% molybdenum, and the balance iron, to obtain the required resistance to deformation at high temperatures and resistance to scaling. A steel of this composition, however, is very expensive and, in addition, has the disadvantage of being incapable of hardening or heat treatment and therefore must be manufactured With a built in natural stress resistance of 80 kg. per sq. mm. (mmfi). In addition such a steel alloy has a very low stress limit as well as a high heat conductivity, poor resistance to wear and abrasion and may be machined only with difliculty.

An important object of my invention is to produce a steel alloy possessing resistance to deformation at high temperatures.

Another object of my invention is to produce a steel alloy having good non-scaling properties.

Another object of my invention is to produce a steel alloy lending itself well to hardening or heat-treatment.

Another object of my invention is to produce a steel alloy having a high stress limit.

Another object of my invention is to produce a steel alloy possessing good heat conductivity.

Another object of my invention is to produce a steel alloy which will resist wear and abrasion.

Yet another object of my invention is to produce a steel alloy of a fine-grained texture which may be easily machined.

A further object of my invention is to produce a steel alloy resistant to corrosion.

Still another object of my invention is to produce an alloy steel which is inexpensive to manufacture.

Other objects of the invention will be apparent during the course of the following description.

To these ends my steel alloy comprises carbon, manganese, chrome, molybdenum, vanadium, and iron within the proportion limits hereinafter recited:

C Mn Cr Mn Va Fe In effecting the present invention I have employed successfully on some occasions the following:

Percent C 0.7 Mn 1 Cr 18 Mo 2.3 Va 0.4 Fe Balanc On other occasions I have successfully employed the following combination:

Percent C 0.8 Mn 1.5 Cr 20 Mo 2.7 Va 0.6 Fe Balance I have found that the chrome molybdenum steel, manufactured within the proportion limits described above, possesses marked advantages. A content in my steel alloy of molybdenum within the limits from 2.3% to 2.7% provides it with resistance to deformation at high temperatutres and the addition to it of chrome within the limits of 18-20%, brings about a high resistance to scaling. I have also discovered that it matches in these properties the earlier described highly expensive nickelchrome steel. In contrast with the said nickel-chrome steel, I have found that another advantage of my alloy steel consists in its ability to harden well, so that the normally required armor of chrome-nickel steel at the stem-end of valves, may be dispensed with. My alloy steel possesses resistance to abrasion and special operating characteristics at the stem part of valves. The heat conductivity of my steel alloy is superior to that of the above-mentioned chrome-nickel steel.

Due to the fine-grained texture of my steel alloy it is corrosion-resistant and is superior in that respect to the nickel-chrorne steel which is made coarse during forging and has therefore a tendency to inter-granular corrosion.

The invention has thus been fully described in a number of examples, but it should be understood that these are given by way of illustration and not of limitation and that many changes can be made in the details without departing from the spirit of the invention.

Having thus described the invention, I claim:

1. As a novel composition of matter, a chrome-molybdenum steel comprising 0.7-0.8% carbon, 1.0-1.5 manganese, l8-20% chromium, 2.3-2.7% molybdenum, 0.4-0.6% vanadium, balance iron.

2. As a novel composition of matter a chrome-molybdenum steel comprising 0.7% carbon, 1% manganese, 18% chromium, 2.3% molybdenum, 0.4% vanadium, balance iron.

3. As a novel composition of matter, a chrome-molybdenum steel comprising 0.8% carbon, 1.5% manganese, 20% chromium, 2.7% molybdenum, 0.6% vanadium, balance iron.

4. A chrome-molybdenum steel alloy for valve cones and the like comprising chromium 18-20%, molybdenum 23-27%, vanadium 0.4-0.6%, manganese l.0-1.5%, carbon 0.7-0.8%, and balance iron.

References Cited in the file of this patent UNITED STATES PATENTS 2,590,835 Kirby Apr. 1, 1952 FOREIGN PATENTS 693,146 Germany July 4, 1940 

1. AS A NOVEL COMPOSITION OF MATTER, A CHROME-MOLYBDENUM STEEL COMPRISING 0.7-0.8% CARBON, 1.0-1.5% MANGANESE, 18-20% CHROMIUM, 2.3-2.7% MOLYBDENUM, 0.4-0.6% VANADIUM, BALANCE IRON. 